Electrical connections between the integrated circuits, without combination with an external contact, are referred to as internal connections, and are normally provided by wire bonds from one semiconductor chip to another. This has the disadvantage that the contact pads to be connected on the integrated circuits must be in the same sequence along their adjacent edges for both semiconductor chips, since crossing of bonding wires can lead to short-circuits. Furthermore, the required bonding tools may restrict the connection density between the integrated circuits on adjacent semiconductor chips to a small number of internal connections.
A further known option is to use a multilayer wiring substrate, whose structured metal layers and correspondingly planned vias allow internal connections between integrated circuits on adjacent semiconductor chips in the semiconductor module. This solution is costly since the high connection density in an interposer greatly increases the packaging costs, not least because additional “build-up” layers are required for the interposer.
Finally, it is possible to produce supplementary connections via additional flip-chip contacts between the semiconductor chips involved and the wiring substrate, in which case the limits of the connection densities in the interposer are also reached very quickly here, so that the costs rise explosively.